1. Field of the Invention
The present invention concerns to an automatic switching circuit of recording mode for image recording/reproducing apparatus, and more particularly to an automatic switching circuit of recording mode which, in the case of monitoring camera for recording intermittently, when motion is detected, recording mode is not only automatically switched for continued recording of pictorial images but the detection of motion is performed in oblique direction of screen.
2. Description of Prior Art
Generally, monitoring camera is widely used in various fields like those for recording situations by using in combination with video casette which can tele-record continuously images on a monitor for a long time, and for coupling image sensors to a monitor in order for video to operate automatically in accordance with the screen variations including the entry of people, and simultaneously for giving off warning sounds.
In U. S. Pat. No. 4,614,966 entitled, "Electronic still camera for generating long time exposure by adding results of multiple short time exposure", in order to prevent detection error of movement magnitude by short time exposure, a technique is introduced to prevent the detection error of movement magnitude by generating long time exposure added by data of short time exposure.
Also, U. S. Pat. No. 4,458,266, entitled "Video movement Detector" discloses a technique of detecting exact movement by dividing TV screen display into detection domain of matrix style and by integrating video signals from said domains and by detecting movement magnitude by way of comparing integrated result with previously-stored values.
However, in the conventional technical constitution as explained in the foregoing, in order to detect movement magnitude, it is inevitable to use memory, and for detection of movement magnitude by storing pixels, it has become necessary to use large capacity of memory.
Even in the case of using 1H(horizontal) retardation element CCD, the drawback of necessitating the use of large capacity of retardation element has existed for comparison between the fields.
Accordingly, it is the object of the present invention to provide automatic switching circuit of recording mode wherein, in the case of monitoring camera, intermittent recording is performed during normal times, and if movement is detected during the performance of intermittant recording, movement against 1 line of oblique direction on the screen is detected by utilizing 1H retardation element, and once movement is detected, continued recording is performed so that retardation element can be saved and simultaneously recording media can be effectively utilized.